Page 208 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

The City & Guilds Textbook: Plumbing Book 1

8 Using Ohm’s law, calculate the voltage in a circuit that has a resistance
of 75 ohms and a current of 2.5 amps.
a 30 volts
b 187.5 volts
c 575.1 volts

d 230 volts
9 What size of earthing cable should be used to bond gas and water mains
pipework?
a 4 mm 2

b 6 mm 2
c 8 mm 2
d 10 mm 2
10 When different metals are present together in a system of pipework,
which of the following types of corrosion is likely to occur?
a Erosion
b Oxidic
c Atmospheric
d Electrolytic
11 A 150-litre cylinder is to be installed within an airing cupboard.
The cylinder will require its temperature raising from 10°C to 60°C.
Calculate the amount of heat energy required.
12 If a cylinder were installed at a height of 3.5 m above the level of
the lowest hot water outlet, what head pressure will be provided at the
outlet?
13 Complete the table below.

Measure of: SI unit Symbol
Area

Volume

Velocity

Density

14 Calculate the thermal expansion in a 3 m length of copper pipe if its
temperature were increased from 10°C to 80°C. Take the coefficient of
linear of copper expansion as 0.000016 m/m/°C.
15 Give two examples of class 2 levers.

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